JP2576508B2 - Thermal printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an improvement in a recording paper feeder of a thermal printer.

[Prior Art] FIG. 3 is a side view of only a transfer portion of a conventional thermal printer disclosed in, for example, Japanese Patent Application Laid-Open No. 58-142887. The drum (30) is configured by, for example, covering the outer peripheral surface of a cylindrical member with rubber or the like. The drum (30) is provided with a clamper (7), which clamps an end of a transfer-receiving member (6), such as paper, which is wound around the drum and thermally transferred. The member to be transferred (6) is a sheet of paper or the like, and its length is at least smaller than the length of the outer peripheral surface of the drum (30). The thermal head (1) is for thermally transferring the ink of the transfer material (8) to the member (6) to be transferred, and is pressed against the drum (30) by a mechanism not shown. For example, in the case of color transfer, the transfer material (8) is coated with three color inks arranged in sequence. Transferred member (6)
Is clamped by the clamper (7) and the drum (3
First, thermal transfer of the first color is performed.
Next, the thermal head (1) is separated from the drum (30), and the drum (30) rotates in the same direction as the direction shown by the arrow A and returns to the initial position, and the next color portion of the transfer material (8) is removed. It is fed to the transfer section of the thermal head (1). The thermal head (1) is pressed against the drum (30) again, and the drum (30) starts to rotate again in the direction shown by the arrow A, and the next color of the transfer material (8) is thermally transferred to the member to be transferred (6). You. In this way, the transferred member (6) reciprocates three times in the case of three colors, for example, to complete the thermal transfer of one sheet.

[Problems to be Solved by the Invention] A conventional thermal printer using a drum requires, for example, a drum of at least 160 mm in diameter when a member to be transferred conforming to Japanese Industrial Standard A3 is used. there were. Also, as the diameter of the drum increases, the radius of curvature of the portion of the drum (30) in contact with the thermal head (1) increases, so that electronic components such as driver ICs provided on the ceramic substrate surface of the thermal head (1) are exposed to the outer surface of the drum. In some cases, the area of the ceramic substrate must be increased to avoid such contact. For this reason, there has been a problem that the thermal head becomes expensive. In addition, when performing color transfer by the pinch roller method or the capstan method, the transfer time is long because the transfer is performed by reciprocating the transfer target member a plurality of times. As a result, there has been a problem that a color shift or the like occurs in the transferred image.

[Means for Solving the Problems] The thermal printer of the present invention runs a timing belt in a fixed direction at a speed substantially equal to the peripheral speed of a platen roller, and a sheet-like cover is provided by a clamper provided on the timing belt. A pulley of a timing belt for clamping an end of the transfer member and running the transferred member while contacting the outer periphery of the platen roller is provided, and a thermal head is brought into contact with a portion of the transferred member that contacts the platen roller. doing.

[Operation] The timing belt always travels in a fixed direction, and the transfer-receiving member clamped by the clamper provided on the timing belt passes between the platen roller and the thermal head for each rotation of the timing belt.

[Embodiment] FIGS. 1 and 2 show a side view and a plan view of a main part of a paper feeding mechanism in an embodiment of the present invention. FIG. 1 and FIG.
In the figure, the left and right timing belts (2, 2)
Having teeth that mesh with the teeth of the timing belt (2, 2);
Pulleys (3a, 3) with teeth fixed to both ends of the shaft (10)
a), toothed pulleys (3
b, 3b) and toothed pulleys (3c, 3c) fixed to both ends of the shaft (12).
Are driven at a constant speed in the direction shown in FIG. Clamper (7)
Is perpendicular to the running direction of the two timing belts (2),
Both ends are fixed to the respective timing belts (2). The platen roller (20) is a pulley (3
c), and its peripheral speed is substantially equal to the running speed of the timing belt. The teeth of the timing belt (2, 2) always mesh with the teeth of the toothed pulleys (3a, 3a), (3b, 3b) and (3c, 3c). Therefore, there is no slippage between the timing belt (2, 2) and each toothed pulley, and the clamper (7) always moves while maintaining a state perpendicular to the timing belt (2). The thermal head (1) is brought into contact with or separated from the platen roller (20) by a mechanism (not shown) so that the thermal head (1) comes into contact with the platen roller (20) only when transferring to the member to be transferred (6). Has been made. The transfer material (8) is supplied from a supply roller (8a), passes between the platen roller (20) and the thermal head (1), and is taken up by a take-up roller (8b).

Next, the operation of this embodiment will be described. In FIG. 1, a sheet-shaped transfer member (6) supplied from below is inserted into a clamper (7) by a feed mechanism (not shown), passing between a platen roller (20) and a thermal head (1) and clamped. Is done. When the thermal transfer is started, the timing belt (2) starts running in the direction shown by the arrow B, the platen roller (20) rotates in the direction shown by the arrow D, and comes into close contact with the member to be transferred (6). The transferred transfer material (8) travels in the direction of arrow C while the ink is transferred to the transfer target member (6) by the thermal head (1). When the transfer of the member to be transferred (6) is completed, the thermal head (1) moves in the direction shown by the arrow E and separates from the platen roller (20). The timing belt (2) further travels in the direction shown by the arrow B, and the clamper (7) returns to the initial position again via the pulleys (3a), (3b) and (3c). Therefore, the transferred member (6) clamped by the clamper (7) also returns to the initial position, and the timing belt temporarily stops at this position. Next, the thermal head (1) moves again in the direction opposite to the arrow E and is pressed against the platen roller (20). Then, the timing belt (2) starts running in the direction of arrow B, and the second color thermal transfer is performed on the transfer target member (6). In this way, the member to be transferred (6) rotates together with the timing belt (2) three times, for example, when performing three-color thermal transfer, and four times, when performing four-color thermal transfer, and when the thermal transfer is completed, the clamper (6). 7) and is discharged. During thermal transfer, it is desirable that the peripheral speed of the platen roller (20) is slightly faster than the traveling speed of the timing belt, and that the transfer member (6) is transported mainly by friction of the platen roller (20).

According to the present invention, the ends of the transferred member (6) are clamped by the clampers provided on the left and right timing belts driven at the same speed, and the timing belt is continuously driven by the traveling of the timing belt. Since the sheet is conveyed in a fixed direction, the diameter of the platen roller can be reduced regardless of the size of the member to be transferred. In addition, since the transferred member is always conveyed in a certain direction and returns to the initial position again by one rotation of the timing belt, the time for transferring the transferred member when transferring a plurality of times on the same transferred member in the case of color transfer. Is shortened. Since the teeth of the timing belt (2,2) always mesh with the teeth of each toothed pulley, there is no slippage between the timing belt (2) and each toothed pulley, and the clamper (7) is always The vehicle travels while maintaining a state perpendicular to the timing belt (2). Further, since the running direction of the timing belt is constant, even if there is a backlash in a gear for driving the timing belt, for example, the transferred image does not affect the stop position of the transfer target member and the transferred image does not have color misregistration. .

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a thermal printer according to the present invention, FIG. 2 is a plan view of the embodiment shown in FIG.
FIG. 1 is a side view showing a main part of a drum part of a thermal printer using a drum system according to a conventional technique. 1: Thermal head 2: Timing belt 3c: Pulley 6: Transfer member 7: Clamper 20: Platen roller

Claims (1)

(57) [Claims] 1. A platen roller for bringing a sheet-shaped member to be transferred and a transfer material into close contact with each other on the surface thereof, provided at both ends of the platen roller, running at a speed substantially equal to the peripheral speed of the platen roller. A pair of timing belts, a clamper erected between the pair of timing belts to clamp an end of the transfer-receiving member, and a platen roller extending the pair of timing belts and clamping the transfer-receiving member clamped to the clamper. A timing belt driving mechanism for driving the pair of timing belts in the same direction and at the same speed so as to run while contacting the outer periphery of the platen; A thermal printer comprising a head.